1. Field of the Invention
The present invention relates to the lightening of the skin, hair, nails and/or lips. The present invention further relates to compositions and methods for lightening the skin, hair, nails and/or lips.
2. Description of the Related Art
By way of background, there is consumer interest in lightening and reducing uneven pigmentation in the skin. Common skin conditions treated include freckles, age spots, dark spots, hyperpigmentation, discoloration, melasma, cholasma, after-burn scar, nail stain, yellowing, and dark circles under the eye.
A variety of materials have been applied to the skin to lighten the skin. Such materials include hydroquinone, kojic acid, licorice and its derivatives, ascorbic acid and its derivatives, arbutin, bearberry, Glycyrrhiza glabra and its derivatives, Chlorella vulgaris extract, perilla extract, and coconut fruit extract. Perilla extract is disclosed as a whitening agent in U.S. Pat. No. 5,980,904 and Japanese Publications Nos. 07025742, 07187989, 10265322, 2001163759 and 2001181173. Coconut fruit extract is disclosed as a whitening agent in Japanese Patent No. 2896815 B2.
Skin and hair pigmentation is determined by the level of melanin present in the epidermis and hair fiber, respectively. For example, three different types of melanin are present in the epidermis: DHI-melanin, DHICA-melanin and pheomelanin. The different types of melanin vary in color or shade. DHI-melanin is the darkest and is blackish in color. DHICA-melanin is brownish in color. Pheomelanin is the lightest and is reddish in color.
Melanin, as described above, is synthesized in specialized organelles called melanosomes within pigment-producing cells (melanocytes). Melanocytes respond to stimuli and regulate melanin synthesis. Melanogenesis is regulated by a variety of environmental and hormonal factors. Melanocytes, which comprise less than 1% of the cells in the epidermis, respond to various signals with alterations in melanin synthesis. Melanin is deposited into organelles known as melanosomes that are transferred to the keratinocytes.
Most conventional topical lightening agents act by interfering with the action of tyrosinase, the enzyme that catalyzes the conversion of the amino acid tyrosine to DOPAquinone. Previously, it has not been known that hypopigmenting could be achieved by inhibiting enzymes “downstream” from tyrosinase in the melanin synthesis pathway by the use of the materials of the present invention. It has now been discovered that the use of the melanin synthesis regulating agent of the present invention inhibits DOPAchrome tautomerase and/or DHICA-polymerase and results in a composition with superior lightening, especially skin lightening.
It is desirable to have a topical composition that provides enhanced levels of lightening, bleaching, hypopigmenting, whitening and/or depigmenting (hereinafter referred to individually and collectively as “lightening” or “lighten”). It is also desirable to have a topical composition that has one or more lightening agents that acted to interfere with the conversion of DOPAchrome to DHI-melanin and DHICA-melanin. It is further desirable to have a topical composition that has one or more lightening agents that act to inhibit or impede the transfer (uptake) of melanin from the melanocytes to the keratinocytes. It is still further desirable to have methods for lightening the skin, hair, nails, and/or lips employing the compositions of the present invention.